The absolute mass of neutrino and the first unique forbidden beta-decay of 187Re

TL;DR

This paper analyzes the electron energy distribution in the unique forbidden beta-decay of 187Re to assess its potential for measuring the absolute neutrino mass, comparable to the KATRIN experiment.

Contribution

It provides the first detailed calculation of the electron energy spectrum for 187Re beta-decay, highlighting the dominance of p-wave emission and deriving the Kurie function relevant for neutrino mass measurements.

Findings

P-wave emission dominates over s-wave in 187Re beta-decay.

Kurie plot near endpoint is approximately linear for massless neutrinos.

The decay's energy spectrum can be used to probe neutrino mass with high sensitivity.

Abstract

The planned rhenium beta-decay experiment MARE might probe the absolute mass scale of neutrinos with the same sensitivity as the tritium beta-decay experiment KATRIN, which will start data taking in 2011 and will proceed for five years. We present the energy distribution of emitted electrons for the first unique forbidden beta-decay of 187Re. It is found that the p-wave emission of electron dominates over the s-wave. By assuming mixing of three neutrinos the Kurie function for the rhenium beta-decay is derived. It is shown that the Kurie plot near the endpoint is within a good accuracy linear in the limit of massless neutrinos like the Kurie plot of the superallowed beta-decay of 3H.